import React, { Component } from 'react';


export default class Count extends Component {
  

    increment = () => {
        // 加法
        const {value} = this.selectNumber
        this.props.jia(value * 1)
    }
    decrement = () => {
        // 减法
        const {value} = this.selectNumber
        this.props.jian(value * 1)
    }
    incrementIfOdd = () => {
        // 奇数加
        const {value} = this.selectNumber
        if (this.props.count % 2 !== 0){
            this.props.jia(value * 1)
        }
    }
    incrementAsync = () => {
        // 异步加
        const {value} = this.selectNumber
        this.props.jiaAsync(value * 1, 500)
    }
  
    render() {
        const {count} = this.props
        return (
            <div>
                <h1>当前求和为：{count}</h1>
                <select ref={c => this.selectNumber = c}>
                    <option value="1">1</option>
                    <option value="2">2</option>
                    <option value="3">3</option>
                    <option value="4">4</option>
                </select>&nbsp;
                <button onClick={this.increment}>+</button>&nbsp;
                <button onClick={this.decrement}>-</button>&nbsp;
                <button onClick={this.incrementIfOdd}>当前求和为奇数再加</button>&nbsp;
                <button onClick={this.incrementAsync}>异步加</button>
            </div>
        );
  }
}
